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What’s the Best Way to Do a Metal Roof Repair?

metal roof repair

If you have a metal roof on your shed, whether standing seam or corrugated metal, it needs to be inspected to see if a metal roof repair is needed at least once a year. It should also be inspected if your area experiences a hailstorm, or you know that a branch or other tree debris has fallen on the roof.

Since metal roofing usually lasts a long time, there will probably be some damage that occurs at some time, needing your attention. If you don’t have a panel that needs replacing, there are ways to do a repair.

Depending on the amount of damage a metal roof repair may need a panel replaced or you may be able to use some sealant to repair the damage to the metal roof.

One thing to remember when walking on your roof to inspect or repair it is to wear rubber-soled shoes. This not only helps you keep from slipping but causes less damage to the metal and its coating while you’re walking around.

Metal Roof Repair for Standing Seam Roofing

Standing seam metal roofing can be dented or even punctured by hail stones. Even without this damage, the paint coating may have been chipped in places. This coating helps protect the roofing metal. Unless your roofing is made from aluminum, holes or chips in the paint coating can eventually lead to a rust spot.

Your best bet in these cases is to keep something on hand to cover any paint chips to prevent rust from starting. Your supplier can recommend the proper paint or coating.

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High winds can catch the edge of your roofing, causing it to move and perhaps loosen. If you or your installer didn’t follow the manufacturer’s specific instructions for installation, this can lead to places that leak or enough instability that a panel or connection can loosen.

Most standing seam roofing is crimped together with the fasteners hidden and kept out of the weather, but that doesn’t mean that they don’t ever have problems, especially if the installation was less than ideal.

Any sealant or sealant tape should be checked when doing your inspection. These products do not last as long as the roofing itself and do need to be replaced when they’re no longer doing the job.

Metal Roof Repair for Corrugated Metal Roofing

Corrugated metal roofing requires a little more care and more frequent inspections. The main difference is that the fasteners are exposed. Even though screws with polycarbonate washers are usually used for fastening, movement of the panels due to wind can loosen the screws or even back them out.

In addition, extra panel movement due to the screws not being fastened down properly can work at the hole the screws go through, enlarging them. Screws being tightened down too much can dent the metal, keeping the washers from laying flush on the metal and reducing the water protection they provide. Even the natural expansion and contraction of the metal with temperature fluctuations can loosen the fasteners.

Other things to look for are cracked sealant between the overlapping panels and any foam closures. Cracked sealant is one of the main reasons for checking your roof periodically. It is one of the main causes of roof leaks, as it has a relatively short lifespan. The lifespan of the sealant you use should be listed on the container. Plan to replace it when its lifetime is up. Many people coat the whole roof with sealant, but again, this too loses effectiveness with age and sun.

How Do You Reseal a Metal Roof?

For any type of metal roof, you need to clean it thoroughly and remove any rust spots, no matter how tiny. If your roof has a lot of small rust spots or you suspect there may be tiny ones that are hard to spot, you can use a rust and oxide remover product, then rinse it with clear water. Seal any overlaps or fasteners that need help before applying any coating.

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Standing seam roofs usually have a protective coating mixed in with the color applied at the factory. Most people only replace the sealant between laps or around flashing. For a roof that is aging, however, you can apply a coating over the whole roof that will further protect it.

For corrugated metal roofs, power wash your roof to remove as much dirt as you can. This will also help you see problems. Use an outdoor caulk to seal around fastener holes. Once the caulk has dried, which usually takes two or three hours, you can put on another coat of sealant.

This can be done with a paint roller made for sealant or a paint roller with a thin nap, using a paintbrush to get into any corners. Wait at least 24 hours for the sealant to dry thoroughly, then apply a second coat.

How Do You Repair a Sheet of Metal Roofing?

You can repair or patch a sheet of metal roofing if it only has a little bit of damage. For instance, a puncture from a hail stone doesn’t mean you have to replace the whole panel.

It’s not recommended for people to try to patch a panel of standing seam roofing themselves. It really takes a professional, especially if the patch is needed on the seam. However, you can patch a seam with polyester fabric seam tape as a temporary holding measure until the professionals can come.

In general, a patch will prove to be the weakest part of the roofing. There may also be problems with the patch’s metal not expanding and contracting as much as the rest of the roof as it’s much smaller than a panel, putting strain on the sealant. That being said, you can put on a temporary patch if you are in a rainy season and a professional installer has a waiting list for service to prevent a leak.

Cut a patch at least two inches wider than the part you want to patch. Keeping scraps from the initial roof installation is a great source for patches. Make sure the roof part that needs patching is absolutely flat.

Make sure the area to be covered by the patch is absolutely clean. Lay your patch over the area and trace an outline around it. Spread urethane sealant in a two-inch border just inside this outline. Put on your patch and press it down well. Sealant spreading out from under the patch is a good sign. In fact, if it doesn’t spread out in one place, that place needs more sealant. Smooth it with a putty knife.

Install panhead screws just long enough to go into the metal around the patch every three or four inches about an inch from the edge so they get into the sealant. You don’t want the screws to get into the roof decking or rafters underneath as this will interfere with the patch expanding and contracting with the roofing panel. If you need to paint the patch, wait until the sealant is fully cured, scuff up the metal patch for paint adherence, then paint or coat the patch.

Corrugated metal roofs can be patched with a piece cut six inches larger than the hole in all directions. Use urethane roofing cement as above to attach the patch. Then cover the patch and an area all around it with glass-membrane fabric, then apply a coat of the urethane cement over the whole area.

Can You Use Roof Cement on a Metal Roof?

Use only urethane or silicone roofing cement on a metal roof. Cement meant for other types of roofing won’t stick as well.

How Do I Find a Metal Roof Leak?

One of the first places to look is around any rust spots. It doesn’t necessarily mean a leak unless the rust has gone all the way through the metal. Hopefully, you’ll inspect the roof often enough to recoat scratched places or rust in the beginning stages.

A patch is another place for potential leaks. As has been mentioned, a patch won’t expand and contract with the rest of the roof, and this movement can break the cement seal, allowing water in.

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Fasteners are another common place for leaks, especially on corrugated metal roofs where the fasteners are exposed. Even screws with washers have problems as the washers age and the sun dries them out, leaving them less effective at keeping out moisture. The natural movement of the metal with temperature changes can also cause the screws to start to back out leaving gaps.

Walking on the roof can cause dents or creases. This can cause water to pool up instead of running off smoothly, and these places are more prone to rust.

Improper installation can cause many problems, including having the seams between panels lift up, allowing water underneath. This is why careful installation is so important.

Things to look for are any puncture holes, rust, missing, loose, or misaligned screws, or those that have been tightened too much. Any panels that have shifted or have become misaligned are another thing to look for. Check the sealant or sealant tape in the overlaps and around any flashing.

Check the roof caps for any damage around flashing, gutters and trim. If you’re afraid you may miss something, you can always call a roofing contractor for a professional inspection for peace of mind.

Can I Caulk a Metal Roof?

You certainly can caulk a metal roof with outdoor caulk. In fact, if you have exposed fasteners, as on a corrugated metal roof, they should be caulked when the original sealant gets too old or is cracked. For resealing overlaps, a silicone sealant is best, as it can move with the metal’s expansion and contraction without breaking the seal. These overlap seals do dry out with age and require reapplication after a time.

How Long Do Metal Roofs Last?

Standing seam roofs can last 50 years or longer. Corrugated metal roofs usually last 30 to 45 years. Of course, the better the maintenance they get, the longer they last. This includes taking care of paint that has been damaged and rust spots that are remedied when they are small.

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Do take note that in coastal areas, such as Florida, the high humidity and salt in the air do affect metal roofs adversely, unless they are made from aluminum. Most steel roofing is coated with zinc to protect it from being affected so much by salt and humidity. They can be recoated with special coatings every few years to keep up the protection.


Metal roofs have become quite popular due to their long lives and the fact that they require less maintenance than some other types. That doesn’t mean, however, that they are problem-free. With regular inspections and maintenance, your roof can easily last quite a long time.

If you are in doubt, check with the manufacturer of your roofing to see how often they recommend inspections. Check out your roof after any hail or windstorms or if any tree debris has fallen on your roof for potential damage. With a little care, you’ll keep your roof in good shape for decades to come.